1. Field of the Invention
This invention relates to sweetened foods and to liquid sweetening agents which contain Aspartame.
2. Description of the Prior Art
.alpha.-L-Aspartyl-L-phenylalanine methyl ester (hereafter referred to as Aspartame) is a low calorie sweetening agent which has a sweetness of good quality and a sweetening intensity about 200 times that of sucrose. Hence, Aspartame is expected to be of great utility in the preparation of foods.
Nevertheless, several problems still exist relating to the handling and storage stability of compositions containing Aspartame. For example, it is known that in foods containing water, particularly foods having a pH of 5.5 or higher or a pH of 2.0 or less, Aspartame decomposes to give a diketopiperazine derivative having no sweet taste, although this decomposition product is nontoxic and completely safe. Similar decomposition takes place in foods intended for long-term storage.
Attempts to improve the stability of Aspartame in water have been made. For example, Aspartame has been covered with gelatin or with a component having a high melting point or one which is water insoluble. Furthermore, it is known to adjust the pH of the composition containing Aspartame to the range in which Aspartame is most stable. These methods are illustrated by chewing gum compositions containing Aspartame in which Aspartame is incorporated in the gum along with an ester gum coating and in which the pH of the water extract of the gum is adjusted to be within the stable range of Aspartame.
However, the use of these conventional methods is impractical in certain foods. For example, the pH adjustment of certain foods is restricted in view of the affect that this adjustment has on the taste of the foods. Likewise, inclusion of insoluble components or components having a high melting point unfavorably affects the manifestation of texture, flavor, sweetness, and the like in many foods. Accordingly, it is no exaggeration to say that the stability of Aspartame for use in foods having a significant water content is the most important problem which prevents putting Aspartame into general practical use.
Additionally, certain problems occur in the handling of Aspartame due to its inherent properties. For example, since Aspartame is generally in the form of needle-like minute crystals, Aspartame powder has a large specific volume and is easily scattered. Therefore, there is a risk of scattering Aspartame during handling operations, which result in the deterioration of the working conditions and at the same time causes lost due to such scattering.
Additionally, while Aspartame has the advantage of not easily absorbing moisture and thereby deliquescing, it has the disadvantage that dispersibility and solubility in water are poor. In utilizing Aspartame in various foods, there is therefore a disadvantage from the aspect of foods processing since Aspartame gives rise to undissolved lumps of powder when attempts are made to dissolve it in water. Thus, the dissolving operation is difficult and takes a long time or is accompanied by a foaming phenomenon.
On the other hand, with the increase in public interest in health and diet, the development of a low calorie sweetening agent which can replace sugar and is also good for dental health has long been sought. Apart from such a general requirement, a means for solving problems associated with conventional products employing sugar, such as browning, tackiness, etc., has long been a major subject of interest in the sweetening industry, along with the development of sweetening agents suitable for the production of beverages, ice cream, etc. In particular, the influence of the sweetening agent on the quality of the final product, the workability of the production processes, the change in the properties due to the sweetening agent, and similar factors are often important when selecting a sweetening agent, especially in beverage, ice cream, and related industries. Furthermore, in cases where a stock solution of a concentrated type is prepared beforehand and where the dilution or bottling of this concentrate is conducted separately, such as in the beverage industry, a high degree of sweetness is required since it is desirable that the volume be as small as possible in order to facilitate transport, storage, and the like. Similar considerations exist where a concentrated stock solution is supplied to a vending machine as a stock solution or a syrup.
In order to meet these varied requirements, sweetening agents such as isomerized sugar, coupling sugar, sorbitol, maltitol, stevioside, saccharin, and the like have been developed and employed. However, these sweetening agents have inherent drawbacks. For example, isomerized sugar, coupling sugar, sugar alcohol, and the like, which are satisfactory with regard to the quality of sweetness and diet, have problems such as a low degree of sweetness. On the other hand, stevioside, saccharin, and the like have a poor quality of sweetness although the degree of sweetness is high.
In the present situation, Aspartame is satisfactory both as to the quality and degree of sweetness and the safety to the diet as described above, but it has problems with the stability and workability properties as described above. Accordingly, there continues to exist a need for improvement in the dispersibility, solubility, and stability of Aspartame compositions.